initial-search-directories

Arguments:
configuration &optional default

Returns (or sets with setf)
the list of directories that will initially appear in the Find In Files
drop-down list of search directory choices.

This property is used only when the Find In Files dialog is created,
and will have no effect if setf'ed later. It is useful mostly for
automatically restoring the search directory choices that were used in
the previous Lisp session (or whenever configuration options were last
saved).